Previous studies of infant memory have used visual attention measures to index retention. These measures are implicit and derive from a model which proposes that preexposed stimuli command less attention than novel stimuli. Retention tests have typically been given within a few minutes of the familiarization procedure and have involved the presentation of a novel stimulus singly or in combination with a preexposed target. It has recently been argued, however, that procedures which involve altered attention do not involve memory processing. As an alternative, it has been proposed that the response-to-novelty involves a perceptual processing strategy only. Although researchers using such techniques typically find a strong response-to-novelty ("retention") after several minutes, research which has attempted to control the extent to which interference material is processed have questioned the robustness of memory. The proposed research will attempt to study memory for acquired associations. The production of a previously trained response in a highly distinctive setting after a given retention interval will constitute the index of retention. The paradigm, conjugate reinforcement with mobiles, will be used to explore factors which influence retrieval in infants as well as the ontogenetic changes in retention which have been presumed to occur over the first postnatal months. Particular focus will be on the role of contextual variables in alleviating forgetting. This technique produces an overt and direct measure of retention which is highly sensitive to qualitative and quantitative changes in test context over periods of several days.